1、 Definition

DALI is the abbreviation of "Digital Addressable Lighting Interface", which is a data transmission protocol. DALI defines the digital communication mode between lighting fixtures and system equipment controllers. DALI is not a new bus, but it supports open systems. The initial goal of designing DALI is to optimize an intelligent lighting control system, which has the advantages of simple structure, convenient installation, easy operation, and excellent functions. It can not only be used for indoor lighting control, but also can be connected with building management system (BMS).

2、 Principles

DALI system is different from BMS, EIB or LON bus system. Instead of expanding it into a system with various complex control functions, it is only used as a lighting control subsystem application, integrated into the BMS through the gateway interface, and can receive the control commands of the BMS or restore the operating state parameters of the subsystem.

The DALI interface communication protocol consists of 19 bits. The first bit is the start bit, the second bit to the ninth bit is the address bit, the tenth bit to the seventeenth bit is data, and the eighteenth and nineteenth bits are stop bits. The unique Manchester code is used to avoid mistakes. The transmission rate of 1200 baud can ensure that the communication between devices is not interfered, and the high level on the control line is 16 V. Each controller on the control line plays a host role in communication, while control appliances such as ballasts on the control line only respond to the command of the host, with distributed intelligent functions.

3、 Application

DALI interface is not only used for dimming fluorescent lamp ballast, electronic transformer of various halogen tungsten lamps, electronic ballast of gas discharge lamps, but also for dimming led. The control equipment also includes wireless receiver, relay switch, input interface, various key control panels and so on, which will make DALI more and more widely used. The controller will be expanded from the smallest office to the multi room office building, and from the single store to the star hotel.

The biggest feature of DALI technology is that a single lamp has an independent address, and the DALI system can precisely control the dimming of a single lamp or a group of lamps. DALI system software can independently address single or multiple lamps on the same high-voltage circuit or different circuits to achieve independent control and arbitrary grouping. Therefore, DALI dimming system brings great flexibility to light control, and users can freely design and adjust corresponding light schemes according to their own needs. This adjustment can still be used during operation after installation, without any change to the circuit.

4、Application Advantages of DALI Dimming System

① Single lamp control is more flexible:

The design of DALI digital control system is simple and convenient. In the design, the DALI digital control system is connected to each other through the digital signal interface and connected to the 2-core control line in parallel. All groups and scenes can be programmed by computer software during installation and debugging, which not only saves wiring costs, but also requires only changing software settings for design modification, re layout and separation without re wiring, which is very simple and easy.

② Digital dimming, accurate, stable and smooth dimming:

DALI is a digital signal, which is different from the analog signal. The signal of 1010 can realize disturbance free control, and will not distort the control signal due to the long-distance voltage drop. Therefore, even if the DALI digital signal control line runs in the same conduit with the strong line, it will not be interfered. DALI signal is bidirectional transmission, which can not only forward transmit control commands, but also feed back the status, fault information, switch and actual brightness value of ballast and lamp to the system.

③ Strong anti-interference ability:

The DALI interface communication protocol consists of 19 bit bits. Bit 1 is the start bit, bits 2 to 9 are address bits, bits 10 to 17 are data, and bits 18 and 19 are stop bits. The unique Manchester code is adopted to avoid bit error. The transmission rate of 1200 baud can ensure that the communication between devices is not interfered. The high level on the control line is 16 V. Each controller on the control line acts as a MASTER function in communication, while control appliances such as ballasts on the control line only respond to the MASTER command to play the role of SLAVE, and the system has a distributed intelligent function.

④ Wide range of applications:

Today, DALI interface is not only used for dimming of fluorescent lamp ballast, but also used for dimming of various halogen lamp electronic transformers, gas discharge lamp electronic ballasts and LED; The control equipment also includes: radio receiver, relay switch input interface. All kinds of key control panels, including LED display panels, have DALI interfaces, which will enable DALI to be used more and more widely. The controller will expand from the smallest office to the office building with multiple rooms, and from a single store to a star hotel.

Intelligent lighting has changed the control mode of light. It used to be a simple switch, but now the light can be automatically adjusted to a comfortable, healthy and energy-saving light environment suitable for the current life/work scene according to subjective factors such as people's living habits, work and rest time.